The proposal, by the Jacksonville-based Medicare contractor First Coast Service Options, would restrict reimbursement for confirmatory tests, which are used to check the accuracy of drug screenings.

In a Tuesday letter to Centers for Medicare and Medicaid Services Administrator Marilyn Tavenner, Bondi cited Florida's "protracted battle against prescription and illicit drug use," and said the new guidelines would "restrict access to one of the most critical tools for identifying drug abuse and misuse."

"Our fear is if Medicare goes down this road, Medicaid will soon follow suit," Bondi said.

The proposal, which is intended to save money and eliminate unnecessary laboratory work, is not a fait accompli. First Coast is taking public input through April 7.

The company declined to comment Wednesday, as did CMS.

First Coast serves as the primary Medicare administrator in Florida, Puerto Rico and the U.S. Virgin Islands, according to its website.

The company released a draft of the proposed coverage guidelines last month. The document caught the attention of the Florida Department of Children and Families, which sent a letter to First Coast on March 7.

"While we support attempts to reduce over-utilization or unnecessary laboratory testing, we remain concerned that curtailing (confirmatory testing) could result in unwelcome public health consequences," Assistant Secretary for Substance Abuse and Mental Health Nevin Smith wrote.

Bondi enumerated those consequences in her March 11 letter to CMS, which oversees contractors like First Coast.

She pointed out that drug screenings done using specimen cups are often unreliable. And a false result could result in a patient being prescribed a deadly combination of drugs.

"Identifying a 'false negative' is typically more important than identifying a false positive because of the life-threatening consequences to a patient if his or her physician prescribes a controlled substance without knowing if the patient is already on a controlled or illicit drug," she said.

"If the ability to perform confirmatory testing, particularly negative confirmatory testing, is eliminated, word will rapidly spread in the drug-using community that all one need do is 'beat the cup' in order to more easily acquire prescription drugs," she said.